1. Field of the Invention
The present invention relates to a fuel tank having a seal member provided at a fuel entry port provided at an upper end of a filler pipe continuously extending to a tank main body for sealing an outer circumference of a nozzle of a fuel filling gun adapted to be inserted into the fuel entry port, or a float valve adapted to close when the fuel level in the tank main body rises and when a vehicle rolls over.
2. Description of the Related Art
A fuel tank of an automobile has a fuel entry port provided at an upper end of a filler pipe extending upwardly from a tank main body, and the nozzle of a fuel filling gun is inserted into a seal member provided at the fuel entry port for refueling. When the fuel level of the tank main body is raised by refueling until the fuel tank becomes full, a float valve is closed to suppress the rise of the fuel level in the fuel tank, and therefore when refueling continues further, the fuel level of the filler pipe then rises. Then, when the nozzle of the fuel filling gun submerges under the fuel level of the filler pipe due to the rise of the latter, an automatic fill-stop device of the fuel filling gun is actuated to thereby prevent the excessive refueling.
In addition, when the fuel level in the tank main body rises due to fueling, vaporized fuel is pushed out into a charging passage from the tank main body through the float valve for adsorption by a canister, whereby the emission of vaporized fuel to the atmosphere is prevented. Moreover, when the fuel level in the filler pipe rises after the float valve closes in accordance with the rise of the fuel level in the tank main body, vaporized fuel pushed out from the filler pipe by the rising fuel is supplied to the canister via the breather pipe and the charging passage.
However, when the automatic fill-stop device fails for some reason to thereby cause an excessive refueling and the fuel level in the fuel filler pipe rises over the limit, since the fuel entry port at the upper end of the filler pipe is closed with the nozzle of the fuel filling gun inserted into the seal member, the internal pressures of the tank main body and the filler pipe rise as refueling continues, whereby the tank main body or the filler pipe may be deformed or the nozzle of the fuel filling gun may be dislocated from the seal member at the fuel entry port, leading to a leakage of fuel.
Further, when excessive fueling occurs due to the failure of an automatic fill-stop device of a fuel filling gun or carelessness of the operator of a fuel filling pump, there is a risk that fuel flows into the canister from the filler pipe after passing through the breather pipe and the charging passage. In addition, since the float valve closes when the vehicle rolls over, although there is no risk that fuel inside the tank main body directly flows into the canister through the charging passage, there is a possibility that fuel inside the tank main body flows into the canister after passing through the breather pipe and the charging passage from the filler pipe.